Nature’s climate controllers help city-dwellers cope with rising heat

Cities can be a lot hotter than surrounding countryside. Anyone who has visited a big city in a heatwave will be familiar with the amplification of heat by concrete, asphalt and stone surfaces. This is termed the urban heat island effect, best seen in an infrared heat image, as cities glow red hot like islands in a sea of cooler landscapes. Buildings, roads and walls act like huge storage heaters that absorb heat from the air during the day and release it as air temperatures cool at night. The dark colours of urban infrastructure exacerbate this effect, as does the lack of green and blue spaces in cities. A recent paper by Robert McDonald and colleagues shows that the urban heat island effect keeps air temperatures in cities up to a third of a degree warmer than the surrounding countryside